Shot shell sealing



June 29, 1954 w. G. RICHARDSON ET A1. 2,632,222

SHOT SHELL SEALING Filed Jan. 26, 1951 Patented June 29,` 1954 UNITEDSTATES PATENT OFFICE SHOT SHELL SEALING Application January 26, 1951,Serial No. 207,927

3 Claims.

This invention relates to a paper cartridge of the type commonly knownas a shot shell, for use in a shotgun, and more particularly to a methodof sealing the end closure of the shot shell. 5

One of the problems associated with sporting ammunition of this type hasbeen to seal the end closure of the shot shell so that it is cornpletelyresistant to the penetration of moisture normally encountered inpractical usage, yet readily opened upon ring without the development ofexcessive internal pressure. It has long been appreciated by thosefamiliar with this art that the degree of resistance to opening of ashot shell is a critical value affecting materiall5 ly the ballisticproperties and consequent performance thereof.

In order to overcome this problem, various modifications in the mannerof closing the end of the shot shell have been suggested at least two ofwhich have been widely adopted. The rst of these is known as thestandard roll crimp method which consists of inserting a card or discknown as the overshot card on top of the shot charge, turning over themouth of the case to form a retaining rim which presses on top of thecard and seals the end of the shell. The main disadvantage of thismethod was therather frequent occurrence of blown patterns, i. e.accentuated scattering of shot beyond the normal area of spread, causedby the emergence of the flat surfaced overshot card which deflects someof the shot completely outside the target area. A second method of shotshell closure devised to overcome this disadvantage, and known as thepleated or star crimp closure was described originally in French Patent593,010 issued to Garkovenko and Fighura in 1925. In this type of shotshell the usual overshot card is omitted and the open end of the shelltube creased into segments which are folded inwardly to form an endclosure `substantially flush with the end of the shell. The main problempresent-y ed by this type of closure was 'to seal the smallcentralaperture or unsealed juncture located at the apex of the foldedsegments in the end of the shell. The effect of moisture on this type ofshell is particularly troublesome not only because it causesdeterioration of the charge and poor ballistic properties resultingtherefrom, but also for its adverse effects on the shot shell tube. Dueto the concentration of paper, in this end of the shell, the entry ofmoisture causes severe dimensional changes and softening so much so infact that after a relatively short time the crimped end of the shellswells to a point where it will no longer chamber in the gun.

Various arrangements have been used heretofore for the purpose ofsealing this closure but none have been entirely satisfactory. Thus forexample U. S. P. 2,242,907 described the use of a paper disc coated onone side with a thermoplastic adhesive composition which completelycovers the end closure of the shell. The paper disc is adapted toclosures of the planar type, i. e. where the at segmental closure is inthe plane of the end of the shell body and not recessed or indented. Themain disadvantage of this type of closure is that the paper disc becomeseasily dislodged in use. This occurs when shells of the type are used inmodern pump and auto loading Shotguns, where the closure discs are tornolf by the action of the breach loading mechanism. Attempts to overcomethe problem centered around improvements in the adhesive compositionsused. Thus for example U. S. P. 2,300,367 and U. S. P. 2,300,368disclose a large number of resin and wax type compositions suitable forsealing planar type closures. However all of these compositions requiredthe use of heat and/ or pressure when applied to the end of the hotshell. A further modification was described in U. S. P. 2,336,065, inwhich the end closure is indented i. e. a small depression made in thepleats in the end of the shell. Into this was spun a disc of plasticself hardening material. After a short period of use it became evidentthat while the recessed end closure containing a plastic disc was farless vulnerable to being dislodged in use, the considerable variation inresistance to opening upon ring of the shell completely upset theballistic properties considered desirable for this type of shell. Thisappeared to be due to the fact ,that uniformity in the thickness of thedisc and the degree of adhesion over the relatively large surface areaof the'end of the shell could not be easily controlled. and as aconsequence successful cornmercial use was never attained.

It is an object of the present invention to pro vide a water resistantclosure for a folded crimp type shot shell. A further object of ourinvention is the production of a simplified method of sealing the endclosure of shot shells of this type.

The objects of the present invention are accomplished by the use of apaste-like adhesive composition applied by injection into the smallcentrally located juncture of the folded segments of the closure, theinner edges of which form the seal. In this manner no disc, either paperor plastic, is required to cover the exterior end of the shot shell.

Our invention will be more clearly understood by reference to theaccompanying drawing in which Figure 1 shows partly in cross section, aloaded shot shell prior to the operation of crimping the end closure.Figure 2 shows a partial perspective view of a shot shell after crimpingand Figure 3 shows the shell with the body top turned over to its nnalrecessed position prior to the sealing operation. Figure 4 is afragmentary sectional elevation view showing the inner edges of thefolded segments of the top shell closure. Figure 5 is a cross section ofa typical sealing gun. Figure 6 is a side elevation of a sealing gunassembled in the gate of a shot shell loading machine. Figure 7 is a topelevation of a section 1-1 of Figure 6.

Referring now in greater detail to the figures of the drawing, in Figure1 the open ended shot shell consists of a wax-impregnated paper body I,shot charge 2, ller wads 3, over powder wad Il, powder charge 5, basewad 6, brass head 'I and percussion cap 3. cap 8 is ignited in shells ofthis type by striking the primer cup with a ring pin, the flame thereofignites the charge of propellant powder 5 firing the shell. In Figure 2,the open end of the shot shell body I has been partially drawn into thefrustoconical form illustrated to form the pleated segments 9. In Figure3, the pleated segments 9 have been pressed further inward and planisheduntil the surface thereof is approximately at right angles to the axisof the shell leaving an un sealed juncture or central aperture I0. Asshown in the figure this segmented end, while substantially at rightangles to the shell axis, is nevertheless recessed below the peripheralbead II and the pleated folds I2 between segments 9 extend further belowthe surface. In Figure 4 the closely abutting segments 9 joined by thedownwardly extending webs I3 dei-lne the position of the inner edges I4of the pleated folds I2, shown in Figure 3, located immediately belowthe central aperture I0. It will be noted that the shot chargev extendsright into the crater-like enclosure formed by the inner edges I4.

Injections of a small amount of the paste-like adhesive composition ofour invention is made through the small central aperture IIS, where itflows into the edges lil of the folds l2 in the form of a globule,causing them to adhere to each other and at the same time sealinglacross the aperture III. It will be evident that substantially all ofthe adhesive as applied in this manner, remains in the crater-likecavity below the aperture I0 at the apex of the segments 9, and is notspread over the top surface itself.

The initial testing of a large number of adhesive compositions suitablefor use in the device of our invention showed that it must be quickdrying in air, and completely water insoluble when dry. In addition itwas found that the viscosity factor of the adhesive was critical forproper op- When the priming composition in eration of the device on aproduction scale. One composition found to meet these requirementscontains a resin modified synthetic rubber dissolved in a suitableorganic solvent, with the addition of a suitable filler such as Frenchchalk or aluminum powder. The use of a large excess of French chalk asller was found to be particularly suitable for use in this adhesivecomposition.

A composition illustrative of our preferred ad- 10 hesive is shown inthe following example:

A modified Vbutadiene-acrylonitrile copolymer, produced by the B. F.Goodrich Rubber Company.

A hydrated calcium silicate-mineral pigment for compounding syntheticrubbers.

The above composition is illustrative only, and it is understood thatvariations in the choice of ingredients may be made, all of which arewithin the scope of our invention.

The following table illustrates a series of comparative tests carriedout to evaluate the water resistance of shells produced according to ourinvention with those produced by heretofore known methods. For thepurposes of the test a random selection of .20 shells of each type wereimmersed, paper ends down, in a bath of cold water for a total period of24 hours. Each shell was then Ichecked at hourly intervals to deter-lmine whether any swelling of the paper casing had occurred. Thosesamples which didnot pass the minimum bore gauge as set :by S. A..A. M.Il (Small Arms Ammunition Manufacturers Institute American) wereconsidered to have failed the test and the results are recorded below.

TABLE Water resistance of shot shells `Shot Shells Failed ImmersionTime, Pleated Crimp Hours CPtoll ump' Paper seai'rhi Percent laecselDisc Seal, Invention,

Percent Percent Results shown in the above table indicate clearly thesuperiority of shells sealed according to the method of our invention asfar as water resistance is concerned. The table `shows also that pleatedcrimp shells sealed by heretofore known methods are less `effectiveagainst moisture penetration than the standard roll crimp shell.

Furthermore tests made of the -shot shells sealed according to themethod of our invention show improved ballistics as exhibited byimproved shot patterns and consequently longer effective range. Theadhesive composition used is ,ad-'- mirably suited to this methodofrsealing 'the end closure of the shot shells. The problem -of laf-ffecting good adhesion between the waxed surfaces to be sealed has beensuccessfully overcome. Fouling of the gun barrel has been eliminated duemainly to the relatively small amount of adhesive required to produce aneffective end closure seal.

It will be understood that While the foregoing is a description of apreferred embodiment of our invention there can be many variations madewithout departing from the spirit and scope thereof.

Having thus described our invention what we claim is:

1. A waterproof shot shell comprising a lacquered wax impregnated paperbody and end closure, said end closure being integral with said body andcomprising a plurality of inwardly folded segments and a waterproofadhesive composition disposed in the aperture formed at the apices ofthe folded segments and along the inner edges of said folded segments,said waterproof adhesive composition comprising` abutadiene-acrylonitrile copolymer, a phenol formaldehyde resin, a ketonesolvent and an inorganic filler.

2. A waterproof shot shell comprising a lacquered wax impregnated paperbody and end closure, said end closure being integral with said body andcomprising a plurality of inwardly folded segments and a waterproofadhesive composition disposed in the aperture formed at the apices ofthe folded segments and along the inner edges of the folded segments,said waterproof adhesive composition being capable of extrusion atordinary temperatures and pressures and comprising a modifiedbutadiene-acrylonitrile copolymer, a

6 phenol formaldehyde resin, a ketone solvent and an inorganic filler.

3. A waterproof shot shell comprising a lacquered wax impregnated paperbody and end closure, said end closure being integral with said body andcomprising a plurality of inwardly folded segments recessed to form adepression slightly within the plane of the end of said body, and awaterproof adhesive composition disposed in the aperture formed at theapices of the folded segments and along the inner edges of the foldedsegments, said waterproof adhesive composition comprising a modifiedbutadiene-acrylonitrile copolymer, a phenol formaldehyde resin, methylethyl ketone solvent and French chalk.

References Cited in the file 0f this patent UNITED STATES PATENTS NumberName Date 396,358 Franklin Jan. 15, 1889 1,397,756 Drysdale Nov. 22,1921 1,504,088 Bransten Aug. 5, 1924 1,646,083 Garkovenko et al. Oct.18, 1927 2,232,634 Roberts et al Feb. 18, 1941 2,242,907 Finlay et alMay 20, 1941 2,300,367 Harmon Oct. 27, 1942 2,300,368 Harmon Oct. 27,1942 2,336,065 Cadham Dec. 7, 1943 2,387,665 Langkammerer Oct. 23, 19452,591,286 Paulve Apr. 1, 1952 FOREIGN PATENTS Number Country Date106,575 Switzerland Sept. 16, 1924 476,326 Great Britain Mar. 3, 1936

